Advanced Placement (AP) Biology Practice Exam

What type of energy transformation occurs during cellular respiration?

1. Potential to kinetic energy

2. Chemical to thermal energy

3. Kinetic to light energy

4. Thermal to electric energy

The correct answer is: Chemical to thermal energy

In cellular respiration, the primary energy transformation involves converting chemical energy from organic molecules, like glucose, into thermal energy, which is often in the form of ATP (adenosine triphosphate). During respiration, glucose is broken down through a series of metabolic pathways, primarily glycolysis, the citric acid cycle, and oxidative phosphorylation. This process releases energy stored in the chemical bonds of the glucose molecule, which is then used to synthesize ATP. ATP serves as a key energy currency in cells, driving various biological processes. When ATP is hydrolyzed, this releases energy that can be captured as thermal energy, which manifests as heat, maintaining the temperature of the organism and facilitating various enzymatic reactions. The other choices involve forms of energy transformations that do not accurately describe the processes occurring during cellular respiration. Therefore, the transformation of chemical energy into thermal energy most accurately characterizes the fundamental change that occurs during cellular respiration.